Array-spectrophotometers for measuring gravity-induced absorption changes (GIACs) during parabolic flights on the AIRBUS-300-ZERO-G

Abstract

Gravity-induced absorption changes (GIACs) were originally measured kinetically by dual wavelength spectroscopy during a series of parabolas on the AIRBUS-300-ZERO-G. In analogy to the more thoroughly understood so-called LIACs (light-induced absorption changes) we assume that GIACs reflect redox-changes of electron transport components such as flavins and cytochromes localized within the plasma membrane. Single beam spectrophotometers for measuring continuous spectra from the UV up to the near infrared range (NIR) are per se significantly less sensitive than dual wavelength spectrophotometers. Nevertheless, we were able to measure the first GIAC-spectra with a patented rapid scan spectrophotometer (RSS) with photomultiplier as light detector. Unfortunately, the RSS is mechanically sensitive to varying g-forces. However, array spectrometers without any motile parts turned out to be mechanically insensitive to strong gravitational changes during parabolas experienced on the AIRBUS-300-ZERO-G [InGaAs diode array in the NIR, CCD in the ultra violet and visible range (UV-VIS), Ocean Optics]. They are also capable of detecting GIACs throughout the complete wavelength range from ultraviolet, through the visible to the near infra red spectral region, if supported by appropriate mathematical routines like Fast Fourier Transform (FFT).